1. Field of the Invention
The present invention relates to the field of voice communications over different types of communications networks. More specifically, the present invention relates to an apparatus which interfaces a wireless IP network and a wide area network or public switched telephone network (PSTN) for voice communications.
2. The Background Art
Public switched telephone networks have been used for many years for voice communication. The typical telephone converts sound waves into analog signals, which are then transmitted through the public switched telephone network to another telephone, which converts the analog audio signals back into sound waves. In recent years, wireless and cellular telephones have been rising in popularity, due to their mobility. Users are no longer tied to a stationary telephone, but are free to carry their telephones with them.
With the advent of computers and fax machines, there arose a need to transmit data in a similar fashion. Due to the fact that analog telephone lines were already in existence in every part of the nation, these lines were also used in the transmission of data. Specific protocols were designed, such as the V.32 protocol, which specified how digital data is encoded into analog signals for transmission over public switched telephone networks.
The apparatus that performs conversion from digital data to an analog telephone signal is known as an analog modem. Analog modems do not require dedicated or specialized lines, as they use pre-existing telephone lines, which are already in existence in nearly every home in the country. The main drawback, however, is in the relatively low speed of transmissions. Current protocols allow only up to about 56 Kbps to be transmitted through an analog phone line, and FCC regulations currently limit this number to 53 Kbps due to power output concerns.
Users who require faster transmission speeds have turned to carriers which allow digital transmission, which not only provide much faster speeds and higher bandwidth, but also reduce errors that occur during transmission. Examples of such carriers are ISDN lines, T1 and T3 lines, and cable lines. ISDN lines are in actuality twisted pair telephone lines. While ISDN service allows a user to obtain digital transmission without a dedicated or specialized line, the inherent physical drawbacks of twisted pair lines limits the amount of bandwidth and speed of such systems. T1 and T3 lines are specialized, dedicated lines (T1 lines can carry up to 1.544 Mbps while T3 lines can carry up to 44.736 Mbps.
Cable modems interface to coaxial cable lines that are typically used for providing cable television signals into homes and they provide a large amount of bandwidth. While it is generally necessary for the cable provider to upgrade the overall cable network system in order to enable Internet access through cable modems, it is generally not necessary to install new lines into homes.
Wide Area Networks (WANS) using wireless data communications techniques and systems have been generally available for many years. Implementations exist which employ microwave radio-frequency (RF) communication systems and frequency-modulated (FM) radio communications. The data rate is generally up to 19.2 Kbps, which is sufficient for the intended class of applications. Frequency-modulated communication techniques include both conventional point-to-point radio and broadcast. These systems include RAM Mobile Data Service using the Mobitex protocol; the Advanced Radio Data Information Service (ARDIS), manufactured by ARDIS Company, Lincolnshire, Ill; and the Cellular Digital Packet Data (CDPD) service.
The ARDIS system, for example, uses a dedicated radio network which includes a number of radio base stations deployed throughout larger metropolitan areas in the United States. The remote devices in the field communicated with the base stations, and vice versa. The base stations are fixed and can cover an approximate radius of 15 to 20 miles when transmitting and receiving. The base stations communicate with a limited number of radio network controllers located at various points throughout the United States. Each radio network controller is responsible for maintaining authorization and registration of the remote terminals. The radio network controllers are further connected to one of three network hubs. The network hubs are connected by dedicated leased lines and are accessed by the customer host applications to send and receive data to and from the remote devices. The customer host applications are also connected to the network hubs by dedicated leased line or through a value added network VAN).
Wireless local area networks (LANS) are used in business applications such as inventory, price verification mark-down, portable point of sale, order entry, shipping, receiving and package tracking. Wireless local area networks use infrared or radio frequency communications channels to communicate between portable or mobile computer units and stationary access points or base stations. These access points are in turn connected by a wired or wireless communication channel to a network infrastructure which connects groups of access points together to form a local area network, including, optionally, one or more host computer systems.
Wireless infrared and radio frequency (RF) protocols are known which support the logical interconnection of portable roaming terminals having a variety of types of communication capabilities to host computers. The logical interconnections are based upon an infrastructure in which at least some each of the remote terminals are capable of communicating with at least two of the access points when located within a predetermined range therefrom, each terminal unit being normally associated with and in communication with a single one of such access points. Based on the overall spatial layout, response time, and loading requirements of the network, different networking schemes and communication protocols have been designed so as to most efficiently regulate the association of the mobile unit with specific access points, and the availability of the communication channel to individual mobile units for broadcasting.
One such protocol is described in U.S. Pat. Nos. 5,029,183; 5,142,550; 5,280,498; and 5,668,803 each assigned to Symbol Technologies, Inc. and incorporated herein by reference.
Another such protocol is described in U.S. Pat. No. 5,673,031. Still another protocol is set forth in the IEEE Standard 802.11 entitled xe2x80x9cWireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specificationsxe2x80x9d available from the IEEE Standards Department, Piscataway, N.J. (hereinafter the xe2x80x9cIEEE 802.11 Standardxe2x80x9d).
The IEEE 802.11 Standard permits either infrared or RF communications, at 1 Mbps and 2 Mbps data rates, a medium access technique similar to carrier sense multiple access/collision avoidance (CSMA/CA), a power-save mode particularly important for battery-operated mobile units, seamless roaming in a full cellular network, high throughput operation, diverse antennae systems designed to eliminate xe2x80x9cdead spotsxe2x80x9d, and an easy interface to existing network infrastructures.
The basic specifications for the communications of audio, video and multimedia that are applicable to the networks pertaining to the present invention are set forth in the International Telecommunications Union Telecommunication Standards Sect (ITU-T) standards H.320-323.
The H.321 recommendation relates to asynchronous transfer mode (ATM) channels, H.322 to guaranteed Quality of Service LANs, and H.323 to packet based systems. Data packets are created from a compressed data stream of digital voice samples. The data packets are formatted for transmission over a data network. Since network latency and packet transmission delays can be disastrous to the intelligibility and quality of real-time phone conversations, a variety of approaches of giving priority of voice packets (or other real-time multimedia packets) over data packets in the network have been proposed, thus allowing delay-sensitive packets to supercede data packets across any network node in any traffic situation. The H.323 recommendation also provides for call establishment and control, including determining the sequencing and timing of establishing and disconnect procedures, as well as the control of the H.323 session after it is established.
To the extent the Internet Protocol or xe2x80x9cIPxe2x80x9d (as set forth in IETF RFC 791) is used as the network layer protocol, the recommendations of the International Multimedia Teleconferencing Consortium""s Voice over IP Forum are also applicable to such a Voice over IP (xe2x80x9cVoIPxe2x80x9d) network. In a VoIP network, the voice signal is digitized, encapsulated into IP packets, and then routed between VoIP capable devices in an IP network. These packets of voice may then be delivered in real time as voice communications, or stored as voice mail.
Communications between a LAN and a wide area network or public switched telephone network are generally performed by communications controller known as a gateway. In the H.323 standard, a gateway generally refers to an endpoint which provides for real-time, two-way communications between H.323 terminals on an IP network and other ITU terminals, telephones on a PSTN, and terminals on other networks. An example of a gateway is the Cisco 3600 series of Cisco Systems, Inc. The Cisco 3600 series is a modular gateway that can be configured to provide gateway functions over a wide variety of communications mediums. These include, among others, analog modem access, ISDN access, digital modem access, and voice and fax access. Other types of interfaces between wired LANs and connected or switched networks such as frame relay and ATM networks are known. For example, the ATM Forum has developed a bridging implementation agreement called LAN Emulation (LANE). LANE relies on a LAN Emulation Server (LES), which performs MAC-to-ATM address resolution; a Broadcast and Unknown Server (BUS), which performs data broadcast; and an optional LAN Emulation Configuration Server (LECS), which performs initialization and configuration.
Prior to the present invention, there has not been a simple and user-transparent way to interface a wireless LAN with the diverse range of currently available public and private networks, including the public switched telephone network (PTSN), cable networks, wide area networks (WAN), cellular telephone networks, and satellite communications networks.
ITU-T Recommendation G.711 (1993) xe2x80x9cPulse Code Modulation (PCM) OF Voice Frequenciesxe2x80x9d
ITU-T Recommendation G.729 (1995) xe2x80x9cCoding of Speech At 8 kbit/s Using Conjugate-Structure Algebraic-Code-Excited Linear-Prediction (CS-ACELP)xe2x80x9d
ITU-T Recommendation H.323 (May, 1996): Visual Telephone Systems and Equipment for Local Area Networks Which Provide a Non-Guaranteed Quality of Service.
ITU-T Recommendation Q.931 (1993): xe2x80x9cDigital Subscriber Signaling System No. 1 (DSS 1)-ISDN User-Network Interface Layer 3 Specification for Basic Call Control
IETF RFC 791 xe2x80x9cInternet Protocolxe2x80x9d. J. Postel. Sep. 1, 1981
IETF RFC 793 xe2x80x9cTransmission Control Protocolxe2x80x9d, J. Postel. Sep. 1, 1981
1. Objects of the Invention
It is an object of the invention to provide an interface between a wireless LAN and a gateway to a voice communications network.
It is another object of the present invention to provide an apparatus including a base station or access point in a wireless LAN and a communications gateway to one or more different communications channels or networks.
It is still another object of the invention to provide a portable wireless desk telephone which communicates with one or more stationary base stations using a packet communications protocol, wherein the base station interfaces to a gateway for connection to an IP network, a WAN, or the PSTN.
It is a further object of the present invention to provide an apparatus which functions as a data downloading station for a portable computer, pen-like bar code reader, or the like, and also transmits the downloaded data to an IP network, a WAN or the PSTN.
It is yet another object of the invention to provide initialization and authorization of a communications handset in a wireless LAN.
It is yet a further object of the present invention to provide an end-to-end real time voice channel through wired and wireless, and connected and connectionless (packet switched) communications channels.
It is an even further object of the invention to provide a method which can be used to accomplish one or more of the above objectives.
Additional objects, advantages and novel features of the present invention will become apparent to those skilled in the art from this disclosure, including the following detail description, as well as by practice of the invention. While the invention is described below with reference to preferred embodiments, it should be understood that the invention is not limited thereto. Those of ordinary skill in the art having access to the teachings herein will recognize additional applications, modifications and embodiments in other fields, which are within the scope of the invention as disclosed and claimed herein and with respect to which the invention could be of significant utility.
2. Features of the Invention
The present invention provides data communications network including a plurality of stationary access points and a plurality of remote mobile units, the mobile units being capable of wirelessly communicating with at least two of the access points when located within a predetermined range therefrom and being normally associated with and in communications with a single one of such access points. A processor is located at one of the access points for detecting a message sent by a first mobile unit and determining from the message whether it is to be routed to another mobile unit or over another channel to another type of communication station; and a gateway is connected to the access point and functions to provide a two-way voice channel of communications between the first mobile unit and another communication station.
The present invention further provides an integral apparatus combining the functions of an access point and a gateway for interfacing a wireless local area network with a wide area network or the public switched telephone network. The apparatus may contain one or more gateways, including a PSTN voice gateway (including xDSL or ISDN interfaces), an analog modem gateway, and others such as a cable modem for connection to a cable network. The apparatus may also include an Ethernet port or serial port for connection to a wired local area network. The apparatus may also include a docking station or well designed to receive the handset or other portable computer device to recharge the battery of the handset or optionally transfer data or control information when the phone or device is secured in the well.
The present invention provides an end-to-end method for handling an outgoing call from a caller using a handset in a wireless local area network, through other communications networks to the called party, including the steps of
detecting when the user activates the mobile handset to make an outgoing call;
receiving in the mobile handset the identification of the destination of the outgoing call from the user;
transmitting a ring signal to a network station corresponding to said destination, said ring signal designed to alert the recipient that a call is attempting to connect; and
transmitting an acknowledgment signal to the mobile handset, said acknowledgement signal designed to alert the user that the cell made by the user is attempting to connect. The present invention further includes the steps of receiving in the handset an indication from the user of the type of call the user desires to make, and determining in the handset whether the user is making a network address call, an intercom call, or a name call.
The present invention further provides a method of operating a data communications network including a plurality of sets of stationary access points and a gateway connected to the access points, and a plurality of remote mobile units, the mobile units being capable of wirelessly communicating with at least two of the access points when located within a predetermined range therefrom. Each mobile unit is normally associated with and in communications with a single one of such access points, and has a single network address that is selectable from a set of network addresses that is utilized by the mobile unit only while such mobile unit is active.
The method includes the steps of storing a set of network addresses available for use by users in a server computer on the network; transmitting a network address request to the server computer from a first mobile unit; and assigning a network address from the set of network addresses available to said first mobile unit. The method further includes providing identification information of the user from said first mobile unit to an authentication server; validating the user privileges by the authentication server and communicating such validation to said first mobile unit; and transmitting the network address associated with the user""s mobile unit to the telephony gateway.